The field of the invention is related to altimeters and vertical velocity altimeters. Current altimeters use an aneroid barometer which mechanically moves three hands around a circular dial to display altitude. Current encoding altimeters use this type display together with various expensive means of converting this information to the code necessary for input to the aircraft transponder for transmission to a ground facility. Current ordinary vertical velocity indicators use an aneroid barometer with a pinhole in the static system to provide information on the rate of altitude change. This information is displayed to the pilot by a mechanically moving hand rotating around a circular dial. Current instantaneous vertical velocity indicators function in a similar manner except that they have a mechanical system which compensates for the delay time in the ordinary vertical velocity indicator. The ordinary vertical velocity indicator's cost is comparable with that of an altimeter, and the instantaneous vertical velocity indicator is roughly three times the cost of the ordinary variety. The current encoding altimeter cost is about 10 times the cost of an altimeter. General devices to warn pilots of an approaching preset altitude are nonexistent due to the fact that they would have to be self-contained and thus be very expensive. Specific devices to warn of minimum altitudes do exist and are exceedingly expensive.
It is noted that many instruments in the panel of the prior art are of the dial variety and due to the large number of these dials situated around the cockpit, assimilation and interpretation of information by the pilot is difficult and time consuming.